Microsoft 365 Exchange Safe Attachment Rule Disabled

 1[metadata]
 2creation_date = "2020/11/19"
 3integration = ["o365"]
 4maturity = "production"
 5updated_date = "2024/05/21"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10Identifies when a safe attachment rule is disabled in Microsoft 365. Safe attachment rules can extend malware
11protections to include routing all messages and attachments without a known malware signature to a special hypervisor
12environment. An adversary or insider threat may disable a safe attachment rule to exfiltrate data or evade defenses.
13"""
14false_positives = [
15    """
16    A safe attachment rule may be disabled by a system or network administrator. Verify that the configuration change
17    was expected. Exceptions can be added to this rule to filter expected behavior.
18    """,
19]
20from = "now-30m"
21index = ["filebeat-*", "logs-o365*"]
22language = "kuery"
23license = "Elastic License v2"
24name = "Microsoft 365 Exchange Safe Attachment Rule Disabled"
25note = """## Setup
26
27The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule."""
28references = [
29    "https://docs.microsoft.com/en-us/powershell/module/exchange/disable-safeattachmentrule?view=exchange-ps",
30]
31risk_score = 21
32rule_id = "03024bd9-d23f-4ec1-8674-3cf1a21e130b"
33severity = "low"
34tags = [
35    "Domain: Cloud",
36    "Data Source: Microsoft 365",
37    "Use Case: Configuration Audit",
38    "Tactic: Defense Evasion",
39]
40timestamp_override = "event.ingested"
41type = "query"
42
43query = '''
44event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:"Disable-SafeAttachmentRule" and event.outcome:success
45'''
46
47
48[[rule.threat]]
49framework = "MITRE ATT&CK"
50[[rule.threat.technique]]
51id = "T1562"
52name = "Impair Defenses"
53reference = "https://attack.mitre.org/techniques/T1562/"
54
55
56[rule.threat.tactic]
57id = "TA0005"
58name = "Defense Evasion"
59reference = "https://attack.mitre.org/tactics/TA0005/"